Add tty console driver for the ml507 terminal

drivers/tty/Kconfig

@@ -398,6 +398,14 @@ config GOLDFISH_TTY
 	help
 	  Console and system TTY driver for the Goldfish virtual platform.
 
+config ML507_TTY
+	tristate "ML507 TTY Driver"
+	select SERIAL_CORE
+	select SERIAL_CORE_CONSOLE
+	select SERIAL_EARLYCON
+	help
+	  Console and system TTY driver for the ML507 terminal.
+
 config DA_TTY
 	bool "DA TTY"
 	depends on METAG_DA

drivers/tty/Makefile

@@ -32,6 +32,7 @@ obj-$(CONFIG_SYNCLINKMP)	+= synclinkmp.o
 obj-$(CONFIG_SYNCLINK)		+= synclink.o
 obj-$(CONFIG_PPC_EPAPR_HV_BYTECHAN) += ehv_bytechan.o
 obj-$(CONFIG_GOLDFISH_TTY)	+= goldfish.o
+obj-$(CONFIG_ML507_TTY)		+= ml507.o
 obj-$(CONFIG_DA_TTY)		+= metag_da.o
 obj-$(CONFIG_MIPS_EJTAG_FDC_TTY) += mips_ejtag_fdc.o
 obj-$(CONFIG_VCC)		+= vcc.o

drivers/tty/ml507.c

@@ -0,0 +1,308 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Simple terminal tty console driver
+ *
+ * Based mostly on the goldfish driver by Google, with some parts
+ * from the SiFive uart driver.
+ */
+
+#include <linux/console.h>
+#include <linux/platform_device.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+#include <linux/slab.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/mm.h>
+#include <linux/serial_core.h>
+#include <linux/of.h>
+
+struct ml507_tty {
+	struct tty_port port;
+	void __iomem *base;
+	struct console console;
+	struct device *dev;
+};
+
+static DEFINE_MUTEX(ml507_tty_lock);
+static struct tty_driver *ml507_tty_driver;
+static u32 ml507_tty_line_count = 8;
+static u32 ml507_tty_current_line_count;
+static struct ml507_tty *ml507_ttys;
+
+static void ml507_tty_do_write(int line, const char *buf,
+				  unsigned int count)
+{
+	struct ml507_tty *qtty = &ml507_ttys[line];
+	void __iomem *base = qtty->base;
+	size_t i;
+
+	for(i = 0; i < count; ++i) {
+		writel(buf[i], base);
+	}
+}
+
+static int ml507_tty_activate(struct tty_port *port, struct tty_struct *tty)
+{
+	return 0;
+}
+
+static void ml507_tty_shutdown(struct tty_port *port)
+{
+}
+
+static int ml507_tty_open(struct tty_struct *tty, struct file *filp)
+{
+	struct ml507_tty *qtty = &ml507_ttys[tty->index];
+	return tty_port_open(&qtty->port, tty, filp);
+}
+
+static void ml507_tty_close(struct tty_struct *tty, struct file *filp)
+{
+	tty_port_close(tty->port, tty, filp);
+}
+
+static void ml507_tty_hangup(struct tty_struct *tty)
+{
+	tty_port_hangup(tty->port);
+}
+
+static int ml507_tty_write(struct tty_struct *tty, const unsigned char *buf,
+								int count)
+{
+	ml507_tty_do_write(tty->index, buf, count);
+	return count;
+}
+
+static int ml507_tty_write_room(struct tty_struct *tty)
+{
+	return 0x10000;
+}
+
+static void ml507_tty_console_write(struct console *co, const char *b,
+								unsigned count)
+{
+	ml507_tty_do_write(co->index, b, count);
+}
+
+static struct tty_driver *ml507_tty_console_device(struct console *c,
+								int *index)
+{
+	*index = c->index;
+	return ml507_tty_driver;
+}
+
+static int ml507_tty_console_setup(struct console *co, char *options)
+{
+	if ((unsigned)co->index >= ml507_tty_line_count)
+		return -ENODEV;
+	if (!ml507_ttys[co->index].base)
+		return -ENODEV;
+	return 0;
+}
+
+static const struct tty_port_operations ml507_port_ops = {
+	.activate = ml507_tty_activate,
+	.shutdown = ml507_tty_shutdown
+};
+
+static const struct tty_operations ml507_tty_ops = {
+	.open = ml507_tty_open,
+	.close = ml507_tty_close,
+	.hangup = ml507_tty_hangup,
+	.write = ml507_tty_write,
+	.write_room = ml507_tty_write_room,
+};
+
+static int ml507_tty_create_driver(void)
+{
+	int ret;
+	struct tty_driver *tty;
+
+	ml507_ttys = kzalloc(sizeof(*ml507_ttys) *
+				ml507_tty_line_count, GFP_KERNEL);
+	if (ml507_ttys == NULL) {
+		ret = -ENOMEM;
+		goto err_alloc_ml507_ttys_failed;
+	}
+	tty = alloc_tty_driver(ml507_tty_line_count);
+	if (tty == NULL) {
+		ret = -ENOMEM;
+		goto err_alloc_tty_driver_failed;
+	}
+	tty->driver_name = "ml507";
+	tty->name = "ttyML";
+	tty->type = TTY_DRIVER_TYPE_SERIAL;
+	tty->subtype = SERIAL_TYPE_NORMAL;
+	tty->init_termios = tty_std_termios;
+	tty->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
+						TTY_DRIVER_DYNAMIC_DEV;
+	tty_set_operations(tty, &ml507_tty_ops);
+	ret = tty_register_driver(tty);
+	if (ret)
+		goto err_tty_register_driver_failed;
+
+	ml507_tty_driver = tty;
+	return 0;
+
+err_tty_register_driver_failed:
+	put_tty_driver(tty);
+err_alloc_tty_driver_failed:
+	kfree(ml507_ttys);
+	ml507_ttys = NULL;
+err_alloc_ml507_ttys_failed:
+	return ret;
+}
+
+static void ml507_tty_delete_driver(void)
+{
+	tty_unregister_driver(ml507_tty_driver);
+	put_tty_driver(ml507_tty_driver);
+	ml507_tty_driver = NULL;
+	kfree(ml507_ttys);
+	ml507_ttys = NULL;
+}
+
+static int ml507_tty_probe(struct platform_device *pdev)
+{
+	struct ml507_tty *qtty;
+	int ret = -ENODEV;
+	struct resource *r;
+	struct device *ttydev;
+	void __iomem *base;
+	unsigned int line;
+
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!r) {
+		pr_err("ml507_tty: No MEM resource available!\n");
+		return -ENOMEM;
+	}
+
+	base = devm_ioremap_resource(&pdev->dev, r);
+	if (IS_ERR(base)) {
+		pr_err("ml507_tty: Unable to ioremap base!\n");
+		return -ENOMEM;
+	}
+	writel('H', base);
+	writel('i', base);
+
+	mutex_lock(&ml507_tty_lock);
+
+	if (pdev->id == PLATFORM_DEVID_NONE)
+		line = ml507_tty_current_line_count;
+	else
+		line = pdev->id;
+
+	if (line >= ml507_tty_line_count) {
+		pr_err("ml507_tty: Reached maximum tty number of %d.\n",
+		       ml507_tty_current_line_count);
+		ret = -ENOMEM;
+		goto err_unlock;
+	}
+
+	if (ml507_tty_current_line_count == 0) {
+		ret = ml507_tty_create_driver();
+		if (ret)
+			goto err_unlock;
+	}
+	ml507_tty_current_line_count++;
+
+	qtty = &ml507_ttys[line];
+	tty_port_init(&qtty->port);
+	qtty->port.ops = &ml507_port_ops;
+	qtty->base = base;
+	qtty->dev = &pdev->dev;
+
+	ttydev = tty_port_register_device(&qtty->port, ml507_tty_driver,
+					  line, &pdev->dev);
+	if (IS_ERR(ttydev)) {
+		ret = PTR_ERR(ttydev);
+		goto err_tty_register_device_failed;
+	}
+
+	strcpy(qtty->console.name, "ttyML");
+	qtty->console.write = ml507_tty_console_write;
+	qtty->console.device = ml507_tty_console_device;
+	qtty->console.setup = ml507_tty_console_setup;
+	qtty->console.flags = CON_PRINTBUFFER;
+	qtty->console.index = line;
+	register_console(&qtty->console);
+	platform_set_drvdata(pdev, qtty);
+
+	mutex_unlock(&ml507_tty_lock);
+	return 0;
+
+err_tty_register_device_failed:
+	ml507_tty_current_line_count--;
+	if (ml507_tty_current_line_count == 0)
+		ml507_tty_delete_driver();
+err_unlock:
+	mutex_unlock(&ml507_tty_lock);
+	iounmap(base);
+	return ret;
+}
+
+static int ml507_tty_remove(struct platform_device *pdev)
+{
+	struct ml507_tty *qtty = platform_get_drvdata(pdev);
+
+	mutex_lock(&ml507_tty_lock);
+
+	unregister_console(&qtty->console);
+	tty_unregister_device(ml507_tty_driver, qtty->console.index);
+	iounmap(qtty->base);
+	qtty->base = NULL;
+	ml507_tty_current_line_count--;
+	if (ml507_tty_current_line_count == 0)
+		ml507_tty_delete_driver();
+	mutex_unlock(&ml507_tty_lock);
+	return 0;
+}
+
+static void ml507_early_console_putchar(struct uart_port *port, int ch)
+{
+	writel(ch, port->membase);
+}
+
+static void ml507_early_write(struct console *con, const char *s, unsigned int n)
+{
+	struct earlycon_device *dev = con->data;
+
+	uart_console_write(&dev->port, s, n, ml507_early_console_putchar);
+}
+
+static int __init ml507_earlycon_setup(struct earlycon_device *device,
+				    const char *opt)
+{
+	struct uart_port *port = &device->port;
+
+	if (!(port->membase || port->iobase))
+		return -ENODEV;
+
+	device->con->write = ml507_early_write;
+	return 0;
+}
+
+OF_EARLYCON_DECLARE(early_ml_tty, "klemens,terminal0", ml507_earlycon_setup);
+
+static const struct of_device_id ml507_tty_of_match[] = {
+	{ .compatible = "klemens,terminal0", },
+	{},
+};
+
+MODULE_DEVICE_TABLE(of, ml507_tty_of_match);
+
+static struct platform_driver ml507_tty_platform_driver = {
+	.probe = ml507_tty_probe,
+	.remove = ml507_tty_remove,
+	.driver = {
+		.name = "ml507_tty",
+		.of_match_table = of_match_ptr(ml507_tty_of_match),
+	}
+};
+
+module_platform_driver(ml507_tty_platform_driver);
+
+MODULE_DESCRIPTION("ML507 TTY console driver");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Klemens Schölhorn <klemens@schoelhorn.eu>");